“Many people think that if they work out every day that’s all they need to do,” says researcher Emma Wilmot, MD, of England's University of Leicester. “But those with jobs that require sitting all day may still be at risk."

Between the time spent driving and seated in front of a desk, computer, or TV, the average adult spends between 50% and 70% of their day sitting down, Wilmot says.

Sitting May Be Hazardous to Your Health

Wilmot's team analyzed 18 studies that together included nearly 800,000 people.

People who sat for the longest periods of time were twice as likely to have diabetes or heart disease than those who sat the least. That was even true of people who did moderate to vigorous physical activity on a regular basis.

Prolonged sitting was also linked to a greater risk of death from all causes, but the strongest link was to diabetes, Wilmot says.

The same research team recently reported that sitting for long periods appears to raise the risk for kidney disease, especially in women.

Thomas Yates, MD, who led that study, says the evidence linking prolonged sitting to poorer overall health is mounting.

“Even for people who are otherwise active, sitting for long stretches seems to be an independent risk factor for conditions like diabetes, cardiovascular disease, and kidney disease,” he says.

Regular Exercise May Not Be Enough

“Right now we are told to get regular exercise, but that may not be enough,” Yates says. “Another important message may be to reduce overall sitting time.”

This may be especially important for people with type 2 diabetes or those at risk for the disease.

Other recent studies have linked sitting for long periods with higher insulin levels.

Stand Up

Yates recommends standing up for two minutes every 20 minutes you spend sitting down, and standing up during commercials when watching TV.

It's not clear if these interventions make a difference, but it's a step in the right direction.

“We aren’t really at the point where we can give specific recommendations,” he says. “But it does appear that the less time spent sitting, the better.”